Student Receivables - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Approximate length of current academic year	210 days
Student receivables, net of allowance for doubtful accounts	$ 1.4	$ 1.3
Minimum [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Student receivables write-off period, days past due	90 days